This calls for at least a $1 and a $5 coin. Now most cash-registers and tills have a limited number of slots for coins, so this means we must abolish the penny and nickle to make room. All prices will be rounded to the nearest dime. Think of the money that will be saved in paper, ink, and plastic for price signs! Look for signs that say: "sale -- only $37.9 -- today only."
If you don't think this is the wave of the future, look at your tax forms. The government wants you to round to the nearest dollar. If we went that far, we could move the range of coinage up to $1, $5, $10, and $20. Do away with those troublesome decimals completely.
If merchants feel they can't compete by shaving a few cents off their prices under this system, let them go back to basics: compete by giving real service to attract customers to their stores. It might just make the world a pleasanter place.